Research On The Principle And Methods Of Torque Measuring Based On Ring Ball Gratings

Torque is one of the most typical mechanical parameters to reflect the performanceof mechanical drive system.In order to ensure the stable and safe operation of the wholesystem,using appropriate torque sensor and measuring method to realize the real-timetorque monitor of mechanical drive system is very important.So the research on digitaltorque measuring principles and methods is suitable for high temperature, strong shock,much dust and other extreme environments, by converting the input mechanicalparameters into the corresponding digital signal connected with computer is to establishmeasuring and control systems, then the automatic measurement and control of torquecan be implemented easily. It is increasingly attached great importance because of thegreat significance and the broad application prospects of the study, and it is also one ofthe great focuses both at home and abroad.Firstly in paper, the development history of torque measuring system is describedbriefly, on this base, the present status of research on torque measuring both at homeand abroad, the application of torque measurement, and the development trend areanalyzed and reviewed. Accordingly, the main research content of paper is fetched outthat is research on the principle and methods of torque measuring based on ring ballgratings.In paper, the definition of torque is briefly introduced, and the principle of torquemeasurement is summarized then. Mainly, the structure and mathematical model for thecore components, named ring ball gratings, of torque measuring system based on thering ball gratings are discussed, and the corresponding direct current excitation modeland the alternating current excitation model are constructed. On this base, the torquemeasuring system model based on ring ball gratings is designed, and its torquemeasuring principle is analyzed and studied in-depth. And the optimization project isanalyzed and discussed for sensor structure aiming at the problem that the amplitude ofmodulated signal is very small.In paper, an important task is analyzing and studying the demodulation method forthe output signal of ring ball gratings sensor. With the wavelet analysis and theself-adaptive neural networks principles, the wavelet neural networks (WNN) model isconstructed and implemented in laboratory virtual instrument engineering workbench(LabVIEW). The demodulation experiments are carried out for the output signal of ring ball gratings sensor using WNN model, and the results indicate that the demodulationeffect is obvious. For improving the convergence performance of WNN, the initialweight parameters are optimized with genetic algorithm.In paper, an another important task is analyzing and studying the phase differencemeasuring principle for the output signals of torque sensor, the phase differencemeasuring principles include zero-crossing method, correlation method and spectrummethod. And the phase difference measuring method based on multivariate linearregression model is put forward. Through the phase difference measuring experimentswith correlation method, spectrum method and multivariate linear regression modelmethod, the important conclusion is gained that the measuring result with correlationmethod is nonlinear with frequency but spectrum method and regression method asfrequency is high. Therefore, the relation between measuring results with regressionmethod and frequency can be simulated with linear function in order to eliminatesystem error. In addition, for reducing the random fluctuation of measuring results, theresults are smoothed with Savitzky-Golay filter and zero phase filter whose effect isobvious.In paper, the experiments are also analyzed and studied for torque measuringprinciple and method based on ring ball gratings sensor. According the principle andmethod put forward in paper, through measuring the phase difference between the twosensors in ring ball gratings torque measuring system, the torsion angle can be gained,and therefore the torque measurement can be realized. The torque measuring systembased on ring ball gratings is constructed with sensors manufactured, LabVIEWsoftware platform and computer. In order to ensure the accuracy of measurements, alarge number of experiments and analyses are carried out on phase difference measuring.In order to reduce measuring error, the multivariate linear regression equation isconstructed and the phase difference measuring system is calibrated by the equation.Through the research on the system principle and method, and the analyses anddiscusses about the experiments results, some very significant conclusion is educed, andthe feasibility of the system principle and method is preliminarily validated.It is hoped that through the research on the torque measuring principle andmethods based on ring ball gratings in paper, can cause the interest of colleagues andachieve the purpose of attracting valuable opinions.